Building tips and hints

[Av8r3400]

Here is an awesome technique that I have found for cutting control cables so that they never fray on the end, yet still fit through the small ferrules on the carburetor control arms.

https://youtu.be/LnTHZhTkg2U

I've used this technique myself with excellent results!

[PapuaPilot]

That method is not recommended for aircraft cables as the heat greatly reduces the strength of the cable.

Another way is to tightly wrap the cable with a little bit of masking tape and cut it with proper cable cutting tool. The tape holds the strands together. I "unscrew" the tape from the cable and the strands usually stay in place and can be inserted into ferrules.

[jrevens]

Something that I've found to work is to put a drop of super glue where it will be cut, then cut with a good pair of wire cutters or dikes. I usually wrap with tape also. That is a cool idea though. Phil's concern is worth considering, but I'm not sure how much degradation of strength might occur where the cable has to be strong. It seems like as long as the cut and "pigtail" is an inch or two away from where the cable has to be clamped that there might not be much concern. Just a thought.

[PaulSS]

That method is not recommended for aircraft cables as the heat greatly reduces the strength of the cable.

I'm interested in why you say that. Surely heating the metal to red hot and then letting it cool afterwards is the same as annealing, which I understand makes metal stronger. I'd like to know why this process would prove to be the opposite.

[Flybyjim]

Surely heating the metal to red hot and then letting it cool afterwards is the same as annealing, ??

I have worked with brass instruments for 40 plus years and doing the above will only soften the brass, we do this for several reasons, one reason is to make the material more pliable to be able to rework the material to reshape, such as removing dents. Another reason is the change the tamber of tone. I would think cable would have some of the same properties. Now if you heat the metal and quench it in water or oil while it is hot will make the material harder but can also become more brittle not just harder. These are my experiences with brass, silver, gold, nickel.

A cable cutter, a tool for this job is not that expensive, the correct tool for the job usually pays for itself in just time savings.

[PaulSS]

These are my experiences with brass, silver, gold, nickel.

Which are not really materials I'd associate with aircraft cables.

Maybe I should have been more specific and mentioned annealing steel; as in steel aircraft cables and not trumpets.

[Av8r3400]

I am using this method for cutting throttle and choke cables. I don't believe it needed on flight surface control cables (rudder). The thimbles and ferrules used in this application are sufficient.

The holding pliers acts as a heat sync and does not allow the heat to travel further up the cable. I played with this technique on several scrap pieces of cable and found that I could immediately put my fingers on the cable above where the pliers were clamped after the heated break was made.

From my experiments the heat effected zone was about 1" in length. This is less than the length of the extra cable left on the assembly. I have no concerns of embrittlement on the cable further up.

With the small diameter wire used in some of the cables - Choke and Throttle - the tape or heat shrink method will not hold. Plus inserting the cable through the crimp ferrule will certainly fray the cable end with out it being secured somehow. This method is far easier than soldering or brazing the end, IMO.

[kmach]

I have used this method too, for installing the 912uls throttle and choke cables. Leave enough tail on the working side ( heat sink). works great.

Flight controls , NO, the amount of strength required to activate a 912 throttle with lighter springs and choke cable , YES.

[PapuaPilot]

Sorry guys, I replied to this late last night before I went to bed. I didn't take time to find a reliable source to back up my statement. I really wanted to nip this tip in the bud. As an A&P-IA (35 yrs) and aviation maintenance instructor (7+ yrs) it's in my DNA to stamp out aviation ignorance.

I also hold a CPL, SEL/SES, MEL with a instrument rating and have just under 10,000 hours flight time. I have been flying and maintaining aircraft that operate in some of the most challenging airstrips in the world (Indonesia, Africa, Asia, Latin/South America). I spent 20 years flying in Papua, Indonesia from 1992 to 2011. I am not trying to boast here, but rather let you know that I am bringing something to the table on this forum. I like to respond to questions and issues that come up and help educate when needed.

The following (in blue) is general in nature, then I will address the issue of cutting cables.

One of the greatest resources we have for the Kitfox is this forum, but any forum or other information we find online may contain information that is wrong. Opinions and hearsay can easily be taken as factual when it's not.

Most of the green A&Ps that come my way have been taught incorrect information at the A&P schools they attended. Sometimes I am really shocked at what is being taught. They think certain things are gospel because they were taught it at A&P school. I show them the correct information so as to stamp out ignorance.

I see the same issue, even more so on this forum; I would guess that the majority of people on this forum are much greener than a freshly minted A&P. Others have spent the time to gain some the knowledge and skills that an A&P has.

Yes, we are building and flying experimental aircraft, but what standard do you want to use. Personally I think it is prudent to stick with what the manufacture and FAA (Transport Canada, etc.) says.

This is from AC43.13-1B

7-147. REPLACEMENT OF CABLES.
Replace control cables when they become worn, distorted, corroded, or otherwise damaged. If spare cables are not available, prepare exact duplicates of the damaged cable. Use materials of the same size and quality as the original. Standard swaged cable terminals develop the full cable strength and may be substituted for the original terminals wherever practical. However, if facilities and supplies are limited and immediate corrective action is necessary, repairs may be made by using cable bushings, eye splices, and the proper combination of turnbuckles in place of the original installation.

b. Cutting and Heating. Cut cables to length by mechanical means. The use of a torch, in any manner, is not permitted. Do not subject wires and cables to excessive temperature. Soldering the bonding braid to the control cable is not permitted.

Lastly, AC 43.13-1B - Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair is available online at https://www.faa.gov/regulations_poli...cumentID/99861 and can be downloaded for free. As the title implies the FAA gives us the acceptable means to inspect, repair (and build) aircraft. I would suggest any one of you that is building an experimental aircraft invest the time and read every chapter that is applicable to the type aircraft you are building. When it comes time to inspect, maintain, repair or alter your plane, AC 43.13 should be your first resource to go to.

To infinity and beyond . . .

[jrevens]

I'm interested in why you say that. Surely heating the metal to red hot and then letting it cool afterwards is the same as annealing, which I understand makes metal stronger. I'd like to know why this process would prove to be the opposite.

Annealing does not make metal “stronger”. In general, it makes it softer and more ductile. Strength is decreased.